Nothing wrong with being sore from a few weeks of training in the wilderness. Running up hills with boulders was always a favorite for me back home - then rolling them to the bottom and starting all over again. Or, even more fun, trying to carry the boulder DOWN the hill. There's a lot of skill in that because*Insert more rambling about how Knuckles spent most of his youth playing with rocks and sticks. Giant rocks and sticks made of whole trees.*